Glacier Express "Swiss Travel Pass 100% coverage" does not include seat reservations?

The STP does not cover seat reservations. On most Swiss trains they are unnecessary, but available for 5 CHF. However, certain tourist type trains like the Bernina Express and Glacier Express require seat reservations, more to do with special services on the train, so they are more than the standard reservation fees.

How to avoid? Take regular trains that operate on those routes. No panorama cars, no headsets with narration of the sights along the way, no table service at your seat, need to change trains along the way.

That is correct. No pass includes reservations. The pass is valid as a ticket on all public transport trains. A reservation is not a ticket, it is an optional extra.
"A 5-course regional menu with wine is included in the reservation fee." - you are paying for the meal.
You do not need the reservation if you travel on the normal hourly train. You will see the same mountains.

Some mountain railways are also not included. See the map here: https://www.sbb.ch/content/dam/sbb/de/infotexte/uebersichtskarte-sts.pdf

I don't believe the meal is included in the reservation fee. That is an extra that is charged for. There is also a lighter lunch option available for less money. Beverages are always extra.

Correct i just tried adding in the lunch and it upped my cost another 100! We'll pack sandwiches...

First time to Switzerland?? Prepared to be shocked by food prices everywhere in Switzerland...except the supermarket.

Thank you for the heads up! I hope the hostels provide a microwave...